yt-dlp's jsinterp.py

https://jxself.org/compiling-the-trap.shtml

I've got subleq+eforth (https://github.com/howerj/muxleq) running in JS which is dead simple to do. No input but I could output ASCII mapping values to an array.

https://esolangs.org/wiki/Subleq

So, yes. yt-dlp runs propietary Youtube JS code defying the original purpose.